This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Glabrous aquatic perennials. Leaves reduced to slender, terete, jointed phyllodes. Involucre and involucels inconspicuous. Flowers white. Calyx-teeth small, persistent. Fruit flattened laterally, rounded at both ends, glabrous; carpels hardly flattened, terete, or somewhat angled in section; ribs rather prominent for the size of fruit, equal; stylopodium conic; styles slender. Oil-tubes solitary in the intervals, two on the commissural side. Seeds nearly terete in section. [Named for Roland M. Harper, a diligent student and collector.]
Three known species, natives of the southeastern United States. Type species: Harperella nodosa Rose.
Harperella vivipara Rose, Contr. U. S. Nat. Herb. 12: 290. 1911.
Annual (?), stem slender, weak, at first erect, afterwards somewhat spreading, 4'-8' long, usually simple, sometimes with one or two branches, in age bearing bulblets at the axils of all the leaves. Basal leaves 2 or 3, 2"-4" long, terete, jointed, bright green, glabrous, hollow, with a scarious stipular sheath at base; stem-leaves similar but shorter, alternate, shorter than the internodes; inflorescence a terminal umbel, with or without other axillary ones; peduncle 1/2'-1 1/2' long; rays 1 1/2" - 5" long; involucre, if present, consisting of one small bract; bractlets of the involucels 4, minute; fruit about 1" long, broader than long.
Banks of the Potomac River, Maryland. July-Oct.
52. C╔LERI Adans. Fam. Pl. 2: 498. 1753.
Perennial glabrous herbs, with pinnate or pinnately compound leaves, and white or greenish flowers in compound umbels. Involucre and involucels small or none. Calyx-teeth obsolete. Petals ovate, mostly inflexed at the apex. Stylopodium depressed, or short-conic. Fruit ovate, or broader than long, smooth. Carpels mostly with prominent ribs, somewhat 5-angled; oil-tubes mostly solitary in the intervals, 2 on the commissural side. Seed terete, or nearly so. [The common name.]
Four or five species, natives of the Old World, southern South America and Australasia, the following typical.
Apium graveolens L. Sp. Pl. 264. 1753.
Glabrous, stem erect, 1°-3° high, several-leaved. Leaves pinnate, the basal and lower ones long-petioled, the upper short-petioled, or nearly sessile; leaf-segments 3 or 5, stalked, or sessile, thin, broadly ovate to oval, coarsely toothed and often incised; 1/2'-1 1/2' long; umbels opposite the leaves, and terminal, 3-7-rayed; involucre and involu-cels small, or none; flowers very small, white, very short-pedicelled; fruit oval, scarcely 1/2" long, the ribs somewhat winged.
In waste places, escaped from cultivation in Virginia, and naturalized on the coast of California. Also in ballast about the seaports. Native of Europe. Old English names, march, ache, marsh parsley, mile. May-July.
Apium Ammi (L.) Urban [A. leptophyllum (DC.) F. Muell.], a slender annual weed of the Southern States and tropical regions, with finely divided leaves and small umbels of white flowers opposite the petioles, found in ballast, and recorded from Missouri, is not definitely known to be established within our area.